1. Technical Field
The present invention relates to a method for manufacturing a branching portion formed in various types of wire harnesses for automobile wiring, for example.
2. Related Art
As a method for preventing an exposure of electric wires at a branch line branching position of a wire harness, a technique disclosed in Japanese Patent Publication No. 3346282. According to the disclosed technique, first, as shown in FIG. 4(a), a longitudinal dimension of electric wires composing a branch line 1 is provided not as a minimum length to directly branch at a branching position P1 from a trunk line 2 but as a length provided with a U-turn formed turning portion 3.
Next, tape winding is applied for uniting and protecting the branch line 1 and branch line 2. Concretely, as shown in FIG. 4(b), tape winding is applied from the terminal side of the branch line 1, to which a connector 4 is connected, toward the branching position P1. At this time, at the branching position P1 side, the tape 5-1 wound around the branching line 1 is wound up to a U-turn turning point P2 of the U-turn turning portion 3, namely, a branch-line-side unilateral portion 3a of the turning portion 3.
Then, as shown in FIG. 4(c), for the trunk line 2, a tape 5-2 is wound from its one end. At this time, at the branching position P1, the tape 5-2 is wound up to the U-turn turning point P2 while uniting electric wires of the trunk line 2 and a branch-line-side unilateral portion 3b of the turning portion 3. By winding tape around the branch line 1 and trunk line 2 as such, an overlapping condition of the tape-wound trunk line 2 and branch line 1 sides is provided between the branching position P1 and U-turn turning point P2.
Then, as shown in FIG. 4(d) and FIG. 5, from the branching position P1 to the U-turn turning point P2, while uniting the previously tape-wound and overlapped electric wires of the trunk line 2 and branch line 1-side unilateral portion 3a, a tape 5-3 is wound around the outer circumference thereof. By the above, the electric wires of the trunk line 2 and branch line 1 are completely covered with the tape (5-1, 5-2, and 5-3). Accordingly, a partial exposure of the electric wires is prevented.
Lastly, as shown in FIG. 4(e), the tape 5-3 wound from the branching position P1 to the U-turn turning point P2 is wound up to the other end side of the trunk line 2, whereby the trunk line 2 is wound with tape across the entire length.
However, the above-described prior art has a problem in that, since the turning portion 3 is formed, the electric wires composing the branch line 1 have a long length, causing an influence on the cost, etc. In addition, it has a problem in that, since the electric wires composing the branch line 1 are bent, this causes breaking of wires or an influence on durability. Furthermore, it has a problem in that an increase in the number of electric wires composing the branch line 1 makes it difficult to form the turning portion 3. Still furthermore, the peripheral size of the branching position P1 is increased and sometimes fails to satisfy its standard. Still furthermore, it has a problem in that, when rigidity of the turning portion 3 is high, since the restoring force of the turning portion 3 (force to return to its original straight state) is increased, it becomes necessary to apply more tape winding, and as a result, the peripheral size of the branching position P1 is further increased.